The present invention relates generally to the field of network transport protocols, and more particularly to multicast network transport protocols.
The Internet Protocol (“IP”) is the principal communications protocol for relaying datagrams across network boundaries. Generally, IP has the task of delivering datagrams from a source host to a destination host based on the IP address in the header section of the datagram. There are three delivery methods supported by IP: unicasting, broadcasting, and multicasting. IP unicasting sends a separate datagram to each recipient host. IP broadcasting sends a single datagram to all hosts on a single network segment (i.e., subnet), even to those not interested in receiving it. Of the three delivery methods supported by IP, multicasting is most practical for one-to-many delivery. The most common transport layer protocol to use multicast addressing is the User Data Protocol (“UDP”). Under UDP, an addressing method is provided for delivery of information to a group of receivers in a single transmission. Each receiver must join the group in order to receive multicast messages sent to the group. Once a source host sends a datagram, nodes in the network (e.g., network switches and routers) replicate the datagram to reach each receiver in the group, such that the datagram is sent over each link of the network only once.